Extensible boom structure

ABSTRACT

A crane adapted to be mounted on a truck and including an extensible boom formed of at least three telescopically arranged sections, with the inner or proximal section having an open rearward or inner end pivotally mounted on a support. The boom includes intermediate and distal or outer sections that are retractible to a position where the inner end of the intermediate section is located a substantial distance beyond the inner end of the inner section in a transport position to provide a substantially balanced structure.

United States Patent [72] lnventors Forrest V. Swanson Wausau; Gerald P. Lamer, Rothschild, Wis.; Lembit Vaerk, Minneapolis; John F. Wilkinson, 1 Savage, Minn. [21] Appl. No. 820,121 [22] Filed Apr. 29, 1969 [45] Patented Nov. 23, 1971 [73] Assignee 1.1. Case Company [54] EXTENSIBLE BOOM STRUCTURE 4 Claims, 9 Drawing Figs.

[52] U.S. Cl 212/55, 52/121, 212/468 [51] Int. Cl B66c 23/06 [50] Fieldol'Search 212/55, 144, 46 A, 46 B; 254/43; 52/121 [56] References Cited UNITED STATES PATENTS 3,398,645 8/1968 Nansel 212/55 3,465,899 9/ 1969 Reuter 212/55 Primary Examiner-Harvey C. Hornsby Atlorne v-Dressler, Goldsmith, Clement & Gordon ABSTRACT: A crane adapted to be mounted on a truck and including an extensible boom formed of at least three telescopically arranged sections, with the inner or proximal section having an open rearward or inner end pivotally mounted on a support. The boom includes intermediate and distal or outer sections that are retractible to a position where the inner end of the intermediate section is located a substantial distance beyond the inner end of the inner section in a transport position to provide a substantially balanced structure.

PATENTEBuuv 23 \911 SHEET 2 [IF 3 EXTENSIBLE BOOM STRUCTURE BACKGROUND OF THE INVENTION Multiple section crane booms are old and well known in the art. In typical prior art arrangements, the sections of the boom are pinned to one another, and great difficulty has been encountered in placing such structure in condition for transportation. For example, in order to place such structures in a road-ready" condition, it is first necessary to lower the boom to the ground, and then uncouple the boom hoist and the load block. The boom extension sections must then be unpinned, and moved to one side, with the boom point section then being placed on skids so as to mate with the boom foot section. The boom point section and boom foot sections are then reassembled, and the extension sections must be loaded on thetruck. The above procedure is time consuming and expensive in terms of man hours, and furthermore, the procedure must essentially be repeated in reverse order to ready the crane for operation.

In order'to obviate the problems connected with cranes hav-- ing multiple sections detachably connected to one another, it has been proposed to pivotally connect at least some of the boom sections to one another, or to arrange the boom sections for telescopic extension and retraction, to provide a more compact structure for transport purposes. Cranes having booms comprised of pivotally connected or telescopically arranged sections have not proven entirely satisfactory, in that even when the sections are moved into their most compact relationship, the center of gravity of the boom structure is still offset a substantial distance from the center of gravity of the truck transporting the crane.

SUMMARY OF THE INVENTION The crane of the present invention has a unique boom structure comprised of a plurality of telescopically arranged sec tions, and the inner or proximal section has an open inner or rearward end, so that the remaining boom sections may be telescoped to a position wherein the center of gravity of the boom structure is substantially coincident with the center of gravity of the truck carrying the crane structure. More particularly, the proximal boom section is of open U-shaped configuration, when viewed in plan, so that the remaining boom sections can move past the pivotal connection of the inner boom section to the upper portion of the crane. The above structure enables the boom to be quickly and easily converted from an operating device to a compact structure for purposes of transportation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary side elevational view of an erection crane formed in accordance with the teachings of the present invention, and illustrating the boom sections in a fully extended operating position;

FIG. 2 is a fragmentary side elevational view, similar to FIG. I, but showing the boom sections in a partially retracted minimum boom length working position;

FIG. 3 is a fragmentary side elevational view similar to FIGS. 1 and 2, but on an enlarged scale and showing the boom structure in a fully retracted road-ready position;

FIG. 4 is a top plan view of the boom structure in a retracted position;

FIG. 5 is a side elevational view of the boom structure in an extended position;

FIG. 6 is a bottom plan view of the boom structure in an extended position; and

FIGS. 79 are end elevational views illustrating different forms of latticed boom constructions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention and modifications thereof, with the understanding that the disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

The improved crane of the present invention is indicated generally at 10 in the drawings, and the crane includes a lower portion 12 adapted to be carried upon an earth traversing vehicle, such as a truck (not shown). Crane 10 further includes an upper portion 14 that is carried upon a turntable 16 which is pivotally mounted upon lower portion 12. A prime mover, such as an engine 18 as provided for driving the ground engaging means of the earth traversing vehicle, and power from engine 18 may be utilized to rotate the turntable 16 through conventional drive structure, not shown. A cab 20 provides an operator station on the upper portion 14 of the crane, as is well known.

Crane 10 includes a multisection boom 24 consisting of a proximal section 26, an intermediate section 28, and a distal section 30. The boom' sections 26, 28, and 30 are mounted for telescopic movement relative to one another between a fully extended position illustrated in FIG. I, a partially extended minimum boom length working position illustrated in FIG. 2, and a'fully retracted transport position illustrated in FIG. 3. As will be evident from the following description, boom sections 28 and 30 can be locked at any intermediate positions between those illustrated in FIGS. 1 and 2. A boom foot support 32 extends upwardly from turntable 16, and the innermost, or boomfoot portion 34 of proximal section 26 is pivotally mounted on support 32 at 36. The outermost end of distal section 30 terminates in a boompoint 38 and a load line 40 extends from boompoint 38 and rearwardly toward the crane upper 12, where it is connected to winches 41. As is well known, winches 41 function to pay out or take in load line 40 to lower or raise a load, as desired.

A jib'44 (FIG. 1) may optionally be connected to the boom 24 at a pivot 42 on the boompoint 38, and in the event that jib 44 is used, a load line 46 extends downwardly from the outer end thereof and back to the crane upper 12, where it is connected to winches 41. If the jib 44 is used, an upwardly extending backstay strut 45 is pivotally connected to boompoint 38, and a backstay line 47 is connected to the jib, as shown in FIG. 1, for pivoting the jib relative to the main boom 24.

Boom sections 26, 28, and 30 are all of open lattice construction, as shown in FIGS. 7-9. The latticed boom structures may be triangular, as shown at 48 in FIG. 7, with the structure including a plurality of longitudinally extending, parallel chords 50 interconnected by inclined lacing members 52. The boom sections may also be generally square, as shown at 54 in FIG. 8, wherein a plurality of longitudinally extending, parallel chord angles 56 are interconnected by inclined lacing tubes or rods 58. A second form of generally square boom structure is shown at 60 in FIG. 9, and the longitudinally extending, parallel chords may take the form of tubes 62 (which may be circular, square or rectangular), or U-shaped channels 62a. Inclined lacing members 64 connect the chords 62 or 6211, and lacing members 64 may be tubes or rods.

As is evident from comparing FIGS. 4-6, the cross-sectional connection of proximal boom section 26 is larger than that of intermediate section 28, which in turn is larger than the crosssectional dimension of distal boom section 30. Any suitable means, such as wear plates, bearings or the like may be associated with boom sections 26 and 28 for guiding and supporting the telescopically arranged sections 28 and 30, respectively. The boom sections illustrated in FIGS. 4-6 are of the FIG. 8 variety, with the subscript a being added to the element of the proximal section 26, the subscript b being added to the elements of the intermediate section 28, and the subscript 0 being added to the elements of the distal section 30.

As can be best seen in FIG. 5, angle members 56a converge rearwardly toward boomfoot 34, and it will be evident from FIG. 4 that no lacing members 580 are provided at the top and bottom of the proximal section 26, so that an open rearward end 66 is provided. Boomfoot 34 is defined by outwardly offset portions 34b (FIG. 6) having openings therein defining the pivot 36 for the boom 24. A generally rectangular sleeve 70 is provided at the outer end of proximal section 26, and sleeve 70 is secured around the outer ends of angles 56a. Locking means 72 is provided at the outer end of sleeve 70 for retaining intermediate section 28 at a selected axial location with respect to proximal section 26, and locking means 72 may be of any kind known to the prior art, such as, for example, a compressive type, or a positive detent type. Illustrative forms of locking mechanisms are shown, for example, in US. Pat. Nos. 2,560,412, 2,819,803, 3,398,645 and 3,171,545.

Means 74 is provided for extending intermediate section 28 relative to proximal section 26, and the extending means includes a double drum winch 78 rotatably mounted upon a support 76 that extends downwardly from sleeve 70. First and second cables 80 and 82 are trained over first and second winch drums 84 and 86, respectively, and cables 80 and 82 extend rearwardly and upwardly around first and second sheaves 88 and 90 on the inner or rearward end 92 of intermediate section 28. Cables 80 and 82 extend upwardly from sheaves 88 and 90 around third and fourth sheaves 94 and 96, respectively, that are mounted on the inner end 92 of section 28, and thence forwardly to fifth and sixth sheaves 98 and 100 that are connected to an upstanding support 102 on sleeve 70. Cables 80 and 82 then extend rearwardly where they are attached by cable securement means 104 and 106, respectively, to the inner end 92 of section 28.

Suitable motor means 108 is carried by sleeve 70 for rotating winch 78, and sheaves 88, 90, 94, and 96 serve as reaction members, so that when winch 78 is rotated in a counterclockwise direction, section 28 is moved outwardly relative to section 26. While the means 74 for extending section 28 relative to section 26 has been illustrated as including two threepart lines, the number of parts can be altered, as desired. Furthermore, the double drum winch 78 can be mounted on top of section 26, or it can be mounted directly upon the upper portion 14 of the crane. Additionally, chain and sprocket means can be substituted for the illustrated cable and sheave means.

The present invention also includes means 110 for extending distal section 30 relative to intermediate section 28. Extending means 110 includes a motor-driven winch 112 secured to the bottom of intermediate section 28 adjacent the outer end thereof. Winch 112 has a single drum 114, and a cable 116 is trained over winch 114, and extends upwardly and forwardly over a sheave 118 that is connected to the outer end of section 28. Cable 116 extends rearwardly from sheave 118 where it is attached by cable securement means 120 to the inner or rearward end 122 of distal section 30. Thus, when winch 112 is rotated in a clockwise direction, section 30 is extended relative to section 28. A locking mechanism 124 of conventional design is provided at the outer end of section 28, for positively securing section 30 at a fixed location relative to section 28.

Boomhoist means 126 is provided for pivoting boom 24 about pivot 36, and for retracting sections 30 and 28. The boomhoist means is of essentially conventional design, and includes a pendent cable means 128 connected between boompoint 38 and a boomhoist cable means 129 that extends around sheave means on a gantry assembly 130. The boomhoist cable means is connected to a motor-driven boomhoist winch means 132 on the crane turntable 16. Thus, when the winch 132 is rotated in a counterclockwise direction, the boom 24 is pivoted in a counterclockwise direction about pivot 36, assuming that the locking mechanisms 72 and 124 are engaged. If the locking mechanisms 72 and 124 are disengaged, the sections 30 and 28 are telescoped inwardly. When the sections 26, 28 and 30 are in the fully retracted position of FIG. 3, the center of gravity of the boom 24 is substantially centered relative to that of the crane 10, but a counterweight 134 (FIG. 4) may be provided to balance the weight of the boom 24, if necessary.

Assuming that the crane is in the working position of FIG. 1, and it is desired to transport the crane to a new site, the following sequence of steps are performed. The boomhoist means 126 is initially actuated to raise the boom to a near maximum working angle to reduce the boomhoist reaction to the boom. The locking mechanism 124, which locks boom section 30 relative to boom section 28 is then released, and the boom hoist means 126 is taken up while the cable 126 is slacked off until section 30 is fully retracted within section 28. The locking mechanism 72 is then released, and the boomhoist means 126 is taken up while cables and 82 are slacked off until section 28 (with section 30 telescoped into it) reaches the minimum working boom length illustrated in FIG. 2. The partially telescoped boom structure is then lowered from the position of FIG. 2 to a horizontal disposition, and the boomhoist means 126 is again taken up while cables 80 and 82 are slacked off until section 28 reaches the fully retracted position of FIG. 3, with an intermediate portion of section 28 adjacent the forward end thereof resting upon boom supports 136 on the crane upper 14. Slacking off of the boomhoist 126 is continued until the gantry assembly 130 falls into a retracted position, and the crane 10 is then in condition to be transported to a new site.

When it is desired to use the crane at the new site, the procedure described in the preceding paragraph is essentially repeated, and the boomhoist means 126 is initially tensioned to raise the gantry assembly 130 into working position, after which the boomhoist is used to raise the retracted boom 24 from the boom supports 136. Extension means is then actuated against the boomhoist tension to extend section 30 relative to section 28 until a predetermined position is reached, at which time locking mechanism 124 is actuated to fixedly secure section 30 relative to section 28. Extension means 74 is then actuated against the boomhoist tension until the lower or inner end of section 28 is forward of the boomfoot support 34 allowing the boom 24 to be raised from the horizontal. The boomhoist means 126 is then actuated to raise the boom to the working angle, and actuation of the extension means 74 is continued until section 28 reaches the desired position relative to section 26. Locking mechanism 72 may then be actuated to positively secure section 28 relative to section 26, but alternatively, section 28 may be supported upon cables 80 and 82 allowing the boom length to be adjusted during the working cycle. As is evident from the foregoing, the crane of the present invention can easily and quickly be readied for transporting, and all of the road-readying steps can be performed by a single individual from the operator's cab.

What is claimed is:

1. In a crane or the like: a ground traversing vehicle defining a support structure; an extensible boom including a proximal section, a distal section, and at least one intermediate section, said sections being positioned in telescoping relationship with respect to one another; means mounting one end of said proximal section on said support structure for pivotal movement about a horizontal axis between a horizontal position and positions inclined with respect thereto; first independent means for moving said intermediate section outwardly relative to said proximal section, said first independent means including at least one cable connected to said intermediate section adjacent the inner end thereof, a winch adjacent the outer end of said proximal section and receiving said cable therearound, and pulley means guiding said cable from said winch to said intermediate section; locking means for retaining said intermediate section at selected positions relative to said proximal section; second independent means for moving said distal section outwardly relative to said intermediate section, and second independent means including a cable connected adjacent the inner end of said distal section, a winch adjacent the outer end of said intermediate section and receiving said lastnamed cable therearound, and pulley means for guiding said last-named cable from said last-named winch to said distal section; locking means for retaining said distal section at selected positions relative to said intermediate section; and means for retracting said distal section relative to said intermediate section to place the outer end of said distal section adjacent the outer end of said intermediate section and for retracting said intermediate and distal sections'relative to said proximal section to place the inner end of said intermediate section and the inner end of said distal section a substantialdistance past the pivotal connection of said proximal section to said support structure, said boom in the retracted position extending outwardly a substantial distance on opposite sides of said pivotal connection, whereby a compact road-ready structure is produced wherein the center of gravity of said boom is substantially aligned with the center of gravity of said vehicle.

2. The invention set forth in claim 1 in which the means for retracting said distal section and said intermediate section includes a boomhoist structure connected between said support structure and distal section for pivoting said boom about said axis.

3. The invention set forth in claim 1 wherein said boom sections are of open lattice construction.

4. The invention set forth in claim 1 in which the outer end of the distal section is disposed outwardly of the outer end of the intermediate section in the retracted position, and wherein the outer end of the intermediate section is disposed outwardly of the outer end of the proximal section in the retracted position.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,622,013 Dated November 23, 1971 FORREST V. SWANSON, GERALD P. LAMER, Inve LEMBIT VAERK and JOHN F. WILKINSON It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 33, insert downwardly after "extends".

Column 2, line 62, insert boom after "intermediate".

Column I, line 69, "and" should be said Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M.FLEICHER,JR. ROBERT GOTTSCHALK Attesting Officer Comnissioner of Patents 

1. In a crane or the like: a ground traversing vehicle defining a support structure; an extensible boom including a proximal section, a distal section, and at least one intermediate section, said sections being positioned in telescoping relationship with respect to one another; means mounting one end of said proximal section on said support structure for pivotal movement about a horizontal axis between a horizontal position and positions inclined with respect thereto; first independent means for moving said intermediate section outwardly relative to said proximal section, said first independent means including at least one cable connected to said intermediate section adjacent the inner end thereof, a winch adjacent the outer end of said proximal section and receiving said cable therearound, and pulley means guiding said cable from said winch to said intermediate section; locking means for retaining said intermediate section at selected positions relative to said proximal section; second independent means for moving said distal section outwardly relative to said intermediate section, and second independent means including a cable connected adjacent the inner end of said distal section, a winch adjacent the outer end of said intermediate section and receiving said last-named cable therearound, and pulley means for guiding said last-named cable from said last-named winch to said distal section; locking means for retaining said distal section at selected positions relative to said intermediate section; and means for retracting said distal section relative to said intermediate section to place the outer end of said distal section adjacent the outer end of said intermediate section and for retracting said intermediate and distal sections relative to said proximal section to place the inner end of said intermediate section and the inner end of said distal section a substantial distance past the pivotal connection of said proximal section to said support structure, said boom in the retracted position extending outwardly a substantial distance on opposite sides of said pivotal connection, whereby a compact road-ready structure is produced wherein the center of gravity of said boom is substantially aligned with the center of gravity of said vehicle.
 2. The invention set forth in claim 1 in which the means for retracting said distal section and said intermediate section includes a boomhoist structure connected between said support structure and distal section for pivoting said boom about said axis.
 3. The invention set forth in claim 1 wherein said boom sections are of open lattice construction.
 4. The invention set forth in claim 1 in which the outer end of the distal section is disposed outwardly of the outer end of the intermediate section in the retracted position, and wherein the outer end of the intermediate section is disposed outwardly of the outer end of the proximal section in the retracted position. 